The present invention relates generally to photovoltaic materials and manufacturing method. More particularly, the invention provides a device for a thin-film photovoltaic cell without a cadmium-based buffer layer and a method for making thereof. The present method and device provide a thin film photovoltaic cell using a copper indium diselenide absorber material and a cadmium-free window buffer material.
Environmentally clean and renewable sources of energy are desired. An example of a clean source of energy is hydroelectric power. Clean and renewable sources of energy also include wind, waves, biomass, and the like. That is, windmills convert wind energy into more useful forms of energy such as electricity. Still other types of clean energy include solar energy.
Solar energy technology generally converts electromagnetic radiation from the sun to other useful forms of energy. For electrical power applications, solar cells are often used. Although solar energy is environmentally clean and has been successful to a point, many limitations remain to be resolved before it becomes widely used throughout the world. As an example, one type of solar cell uses crystalline materials, which are derived from semiconductor material ingots. These crystalline materials can be used to fabricate optoelectronic devices that include photovoltaic and photodiode devices that convert electromagnetic radiation into electrical power. However, crystalline materials are often costly and difficult to make on a large scale. Additionally, devices made from such crystalline materials often have low energy conversion efficiencies. Other types of solar cells use “thin film” technology to form a thin film of photosensitive material to be used to convert electromagnetic radiation into electrical power. Similar limitations exist with the use of thin film technology in making solar cells. That is, efficiencies are often poor. Additionally, thin-film photovoltaic cells traditionally use exotic elements including cadmium, mercury, or telluride, which substantially limit the applications and cause environmental side effects. Often, such thin-film solar devices are difficult to handle during their manufacture processes because of these toxic materials.
From the above, it is seen that improved techniques for manufacturing photovoltaic materials and resulting devices are desired.